Puzzling coil

[Teleno]

Built this simple coil: 27,5 cm diameter, 21 turns of 0,4mm enameled wire. Resistance os 0,8 Ohm.

Coil calculators give inductance values in the range of 330uH - 350uH. However, my inductor meter says 9uH (!).

When attached to a Colpitts oscillator it doesn't oscillate while a commercial ferrite coil of 330uH does.

The only explanation I can come with is that the turns are shorted, but in that case 0,8 Ohm still seems to high. I can't think of anything else.

What gives?

[ivconic]

Built this simple coil: 27,5 cm diameter, 21 turns of 0,4mm enameled wire. Resistance os 0,8 Ohm.

Coil calculators give inductance values in the range of 330uH - 350uH. However, my inductor meter says 9uH (!).

When attached to a Colpitts oscillator it doesn't oscillate while a commercial ferrite coil of 330uH does.

The only explanation I can come with is that the turns are shorted, but in that case 0,8 Ohm still seems to high. I can't think of anything else.

What gives?

100% shorted, no doubts.

[Qiaozhi]

Built this simple coil: 27,5 cm diameter, 21 turns of 0,4mm enameled wire. Resistance os 0,8 Ohm.

Coil calculators give inductance values in the range of 330uH - 350uH. However, my inductor meter says 9uH (!).

When attached to a Colpitts oscillator it doesn't oscillate while a commercial ferrite coil of 330uH does.

The only explanation I can come with is that the turns are shorted, but in that case 0,8 Ohm still seems to high. I can't think of anything else.

What gives?

I did a quick calculation of the coil resistance, based on your details above, and it looks like it should be around 2.4 ohms. As Ivconic said - must be a shorted turn.